System for controlling coagulant treatment based on monitoring of plural parameters

ABSTRACT

A system is disclosed for controlling the amount of treatment composition, e.g., cationic coagulant, to be introduced into an aqueous medium, e.g., a laundry waste water, having a content of fats, oils and/or grease (FOG) which is to be reduced. This system comprises a plurality of detectors each of which is adapted to determine a parameter, other than the FOG level, of a material comprising the components of the aqueous medium and to provide a determined signal indicative of the determined parameter; and an automatic processor provided with a relationship of the amount of treatment composition to be introduced into the aqueous medium to reduce the FOG of the aqueous medium to a given level as a function of the plurality of determined signals, and adapted to receive the plurality of determined signals and to provide a control signal to a source of treatment composition to control the amount of treatment composition introduced from the source of treatment composition into the aqueous medium.

BACKGROUND OF THE INVENTION

The present invention relates to a system for controlling the amount oftreatment composition to be introduced into an aqueous medium having acontent of fats, oils, and/or grease which is to be reduced. Moreparticularly, the invention relates to a system for controlling theamount of treatment composition, such as coagulant, to be introducedinto a waste water, such as a laundry waste water, having a content offats and/or oils and/or grease which is to,.be reduced, for example, byseparation of such fats, oils and grease from an aqueous phase.

Various aqueous media include or become contaminated with one or morefats and/or oils and/or grease. As used herein, the term "FOG" refers tofats and/or oils and/or grease. For example, the water utilized in aconventional laundry operation becomes contaminated with FOG, forexample, from the articles which are laundered and/or from thedetergents and other additives used in the operation. This laundry wastewater often cannot be disposed of directly into a publically ownedtreatment works because of the relatively high FOG concentration.

One approach to overcoming this problem has been to add a coagulant, forexample, a cationic coagulant such as one or more cationic polymers andthe like, to the laundry waste water so as to coagulate and separate atleast a portion of the FOG, from the laundry waste water. Thesecoagulated materials are separated from the remainder of the aqueousmaterial and disposed of, for example, as a sludge in a land fill orother suitable disposal facility. The resulting aqueous phase has asufficiently reduced FOG concentration to be conveniently disposed of ina publically owned treatment works.

One potential difficulty with such a treatment process is that the FOGlevel in the waste water varies over time so that the demand forcoagulant also varies. In general, as the FOG level in a waste waterincreases, the amount of coagulant needed to provide an aqueous phasehaving an acceptably low FOG concentration also increases. Thus, theamount of coagulant used is often set at a relatively high level toinsure that the water entering the publically owned treatment works isacceptable. The amount of coagulant used in this type of process isoften in excess of that needed to provide the acceptably low FOGcontent.

Directly analyzing an aqueous medium for FOG is often a tedious and timeconsuming task which may involve taking a sample of the waste water andperforming various separation steps to determine the FOG content of thewaste water. The time involved in performing these steps may be such asto render the FOG determination obsolete in that the waste water beingtreated may have a different level of FOG than that determined via thisrelatively complex procedure.

SUMMARY OF THE INVENTION

New systems for controlling the amount of treatment composition to beintroduced into an aqueous medium having a FOG concentration which is tobe reduced have been discovered. The present systems provide a veryeffective, in terms of time and cost, way to control the amount oftreatment composition used to reduce the FOG level in an aqueous medium,such as a laundry waste water.

The present system is preferably operated without taking individualsamples of the aqueous medium for testing. Also, the analytical testingwhich is involved preferably is such that the FOG level is not directlydetermined. Conventional measurements are made and correlated with orrelated to the FOG level which relationship is then used to control theamount of treatment composition to be introduced into the aqueous mediumto reduce the FOG level. The present system can be, and preferably is,used "on-line", meaning that the present system is used on a real timebasis, and monitors and controls the aqueous medium as it is beingprocessed, more preferably on a continuous basis.

In one broad aspect, the present system comprises a plurality ofdetectors each of which is adapted to determine a parameter, other thanthe FOG level, of a material comprising the components of an aqueousmedium and to provide a determined signal indicative of the determinedparameter. An automatic processor, preferably an electronicmicroprocessor, is included. This automatic processor is provided with arelationship, preferably an empirical relationship which isexperimentally determined, of the amount of treatment composition to beintroduced into the aqueous medium to reduce the FOG level of theaqueous medium to a given level as a function of the plurality ofdetermined parameters or determined signals. The automatic processor isadapted to receive the plurality of determined signals from theplurality of detectors and to provide a control signal to a source oftreatment composition, for example, including a composition pump and acomposition supply tank, to control the amount of treatment compositionintroduced from the source of treatment composition into the aqueousmedium.

The use of detectors which can determine a parameter of a compositionwithout the necessity of removing a sample of the composition is areparticularly useful in the present invention. Thus, the detectors candetect the required parameters even while the aqueous medium is beingtreated. The control signal is based on these determined parameters anda very effective control loop is provided so that a cost effectiveamount of treatment composition is provided to the aqueous medium evenwith variations in the composition of the aqueous medium.

These and other aspects and advantages of the present invention are setforth in the following detailed description and claims, particularlywhen considered in conjunction with the accompanying drawings in whichlike parts bear like reference numerals.

In describing the drawings, the aqueous medium is a laundry waste waterand the treatment composition is a coagulant, in particular a cationiccoagulant. However, it should be understood that the present, inventionis applicable to any aqueous medium which is to be treated and to anytreatment composition useful in treating such aqueous medium, forexample, to reduce the FOG content of the aqueous medium. The inventionis particularly useful in situations where a waste water stream has aFOG level which is to be reduced using a liquid coagulant composition.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic illustration showing one water treatmentinstallation using an embodiment of the present control system.

FIG. 2 is a detailed schematic illustration of the embodiment of thepresent control system used in FIG. 1.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a laundry waste water treatment installation, showngenerally at in which is utilized an embodiment of the present controlsystem, shown generally at 10. Waste water from laundry 12, whichcontains a substantial amount of fats, oils and grease (FOG), is passedthrough line 14 to an intermediate storage tank 16. The FOG content orlevel in this waste water is from the articles which were laundered inlaundry 12, as well as from the detergents and other additives used bylaundry 12. In any event, the FOG level of the waste water must bereduced before the water stream can be disposed of in a publically ownedtreatment (water treatment) works.

To coagulate the FOG in the waste water, a liquid cationic coagulantcomposition, such as that sold by Dober Chemical Corporation under thetrademark DWT 5222, is added to the waste water exiting intermediatetank 16 through line 18. After the coagulant has been added, the mixedwaste water/ coagulant is passed to a clarification section 20 wherecoagulated FOG-containing material is separated from an aqueous phase.This FOG-containing material is removed from the clarification section20 and passed, as a sludge, to a landfill operation or other suitabledisposal facility. The clarified aqueous phase or water is passedthrough line 22 to a publically owned treatment works.

One important variable in determining the amount of coagulant to be usedto treat the laundry waste water is the FOG level in the waste water. Ingeneral, the higher the FOG level, the more coagulant that is needed toreduce the FOG level of the clarified water to an acceptable level, thatis a FOG level acceptable so that the clarified water in line 22 can bepassed to a publically owned treatment works. However, a directmeasurement of the FOG level in the waste water often requires thatsamples of the waste water be collected and separated into variousfractions, with one or more of these fractions being further analyzed todetermine the concentration of fats, oils and grease in the waste water.Such analytical procedures are tedious and time consuming and may resultin a FOG level determination which is outdated or obsolete in that suchdetermined FOG level does not reflect the FOG level of the waste watercurrently being treated.

The present invention overcomes these concerns. The present controlsystem 10 provides for determining or monitoring a plurality ofparameters of the waste water/coagulant mixture in line 18. The mixturein line 18 which is monitored includes an at least partially effectiveamount of the coagulant. In other words, the point or points along line18 where the material flowing in line 18 is monitored are locateddownstream of the location at which the coagulant is introduced intoline 18. The FOG level of this mixture is not included among theparameters determined or monitored. In fact, each of the parametersdetermined by control system 10 preferably can be determined withouttaking individual samples from line 18. Based at least in part on theseparameter determinations, control system 10 provides a control signalthrough line 24 to coagulant pump 26 which is operated in response tothe control signal in line 24. Based upon this control signal, coagulantpump 26 passes a variable amount of coagulant from coagulant storagetank 28 through line 30 into line 18. The amount of coagulant enteringline 18 is controlled so that the water in line 22 is such as to beacceptable for disposal in a publically owned treatment works. Inaddition, and importantly, the amount of coagulant is controlled so thatno substantial or undue excess of coagulant is used to achieve, an"acceptable" aqueous stream in line 22. In other words, control system10 controls the amount of coagulant introduced into line 18 so that"acceptable" water or aqueous medium is produced in line 22 whilesubstantially minimizing the actual amount of coagulant used.

Each of the lines which transmit signals is shown in shadow. The presentsignals are preferably electrical or electronic in nature, although oneor more other types of signals may be employed.

Referring now to FIG. 2, control system 10 is shown in more detail.Control system 10 includes an electronic microprocessor 32, a streamingcurrent detector 34, a turbidimeter 36, a pH meter 38, and a flow meter40. Any suitable streaming current detector 34, turbidimeter 36, pHmeter 38 and flow meter 40 may be used in control system 10 providedthat such components are capable of transmitting a signal, e.g., anelectrical or electronic signal, to electronic microprocessor 32. Eachof these system components may be chosen from devices which areconventional and well known in the art. For example, useful electronicmicroprocessors include, but are not limited to, microprocessors sold byAllen Bradley under the trademark SLC-500, and the Series 9microprocessors sold by General Electric; useful streaming currentdetectors include, but are not limited to, such detectors sold byChemtrac, and such detectors sold by Milton Roy under the trademarkSCD-4200; useful tubidimeters include, but are not limited to, Beckmanturbidimeters and turbidimeters sold by Hach under the trademark SurfaceScatter 6; useful pH meters include, but are not limited to, pH metersand/or pH controllers sold by Beckman and Great Lakes Instruments; anduseful flow meters include, but are not limited to, doppler meters soldby Polysonics and flowmeters sold by Great Lakes Instruments under thetrademark Magmeter. Coagulant pump 26 may be any suitable pump capableof delivering the required amount of coagulant from storage tank 28 toline 18. Coagulant pump 26 is preferably a variable flow device, that isa device which is capable of delivering a controlled, variable amount ofcoagulant to line 18 in response to a control signal in line 24 fromelectronic microprocessor 32. Examples of pumps which may be usedinclude, but are not limited to, electromagnetic pumps, such as thechemical metering pumps sold by Liquid Metronics, Inc. under thetrademark LMI Series D4.

The streaming current detector 34 measures the electrical charge of thewaste water/coagulant mixture flowing through line 18. The turbidimeter36 measures the turbidity of the mixture in line 18. The pH metermeasures the pH of the mixture in line 18. The flow meter 40 measuresthe flow rate of the mixture in line 18. Each of the streaming currentdetector 34, turbidimeter 36, pH meter 38 and flow meter 40 include aprobe or similar device which is passed into line 18 so that adetermination of the relevant parameter can be made while the laundrywaste water/coagulant mixture is flowing through line 18. No samples ofthis mixture are required to be removed from line 18 to make thesedeterminations. Preferably, each of the components 34, 36, 38 and 40measure the relevant parameter of the mixture in line 18 on asubstantially continuous basis so that electronic microprocessor 32 isprovided with signals indicative of the current conditions in line 18.

A conventional electrical power source 42 is used to power each of thecomponents 32, 34, 36, 38 and 40 of control system 10.

Once the parameter determinations are made, signals in lines 44, 46, 48and 50 are provided from the components 34, 36, 38 and 40, respectively,to electronic microprocessor 32 which receives the signals and processesthe signals, as described below.

Over a period of time, for example, over a two to three week period,during which the overall waste water system 1 is operated without usinga control signal from line 24 (for example, using manual control ofcoagulant pump 26), a relationship is developed between the values ofthe parameters determined by components 34, 36, 38 and 40 and the amountof coagulant needed to be introduced into line 18 to provide a clarifiedwater phase in line 22 which is acceptable to be treated in a publicallyowned water treatment works. This relationship may comprise one or morealgorithms which, overall, define the amount of coagulant needed toprovide an acceptable aqueous phase in line 22 as a function of each ofthe parameters determined by components 34, 36, 38 and 40 or as afunction of each of the signals from lines 44, 46, 48 and 50.

Such experimentally developed, empirical relationship is manuallyprovided to electronic microprocessor 32 through keyboard 52, forexample, an operator interface sold by Spectrum under the trademark SOE201. Electronic microprocessor 32 is programmed, for example, throughkeyboard 52 using conventional and well known computer softwareprogramming techniques, to process the signals from lines 44, 46, 48 and50 in accordance with the above-noted relationship and provide a controlsignal through line 24 to coagulant pump 26 to control the flow ofcoagulant into line 18. Thus, electronic microprocessor 32 receives theindividual signals from lines 44, 46, 48 and 50, appropriately uses thevalues of each of these signals in the above-noted relationship,computes a value for the control signal, and passes this control signalthrough line 24 to coagulant pump 26. For example, electronicmicroprocessor 32 using the above-noted relationship and the signalsreceived from lines 44, 46, 48 and 50, determines whether more, less orthe same amount of coagulant is to be introduced into line 18 to obtainan acceptable aqueous phase in line 22. Based on this determination,electronic microprocessor 32 generates and sends a control signalthrough line 24 to coagulant pump 26 causing the coagulant pump tointroduce more, less or the same amount of coagulant into line 18. Sincethis control process is at least periodically, preferably continuously,repeated, the amount of coagulant introduced into line 18 is effectivelycontrolled so as to obtain an acceptable aqueous phase in line 22,without using an unduly excessive amount of coagulant.

The correctness of the information provided via keyboard 52 is visuallymonitored using a monitor 54 which is connected with keyboard 52.Although electronic microprocessor 32, keyboard 52 and monitor 54 areshown as separate components, they may be provided as a single, integralunit.

The relationship between the determined parameters and the effectiveamount of coagulant to be used depends on a number of factors, many ofwhich are site specific, for example, the composition of the wastewater, equipment sizes, lengths and diameters of pipes between pieces ofequipment, placement of control system 10 and the like. Thus, the actualrelationship used for control purposes is preferably developed at andfor the site where it is to be used. Although the control relationshipmay vary from site to site, it is often, though not always, true thatthe amount of coagulant needed to achieve an aqueous phase which isacceptable for disposal to a publically owned treatment works increasesas the electrical charge of the waste water-containing materialincreases; as the turbidity of this material increases; as the pH ofthis material increases; and as the flow rate of this materialincreases.

In certain instances, only two or three of the components 34,36,38 and40 are used in control system 10. Very useful results are obtained ifthe control system 10 includes streaming current detector 34 andturbidimeter 36, but not the components 38 and 40.

After the initial period of time during which the above-notedrelationship is developed, the control system 10 operates substantiallyautomatically, i.e., without human intervention, and can be operated ona continuous, on-line basis to control the treatment of the waste waterfrom laundry 12.

Based on the parameters determined by components 34, 36, 38 and 40, andthe relationship between the determined parameters and the amount ofcoagulant needed to be introduced into line 18 to produce an acceptableaqueous phase in line 22, electronic microprocessor 32 transmits acontrol signal through line 24 to coagulant pump 26 which operates inresponse to this control signal to provide a controlled amount ofcoagulant from storage tank 28 via line 30 into line 18.

The operation of the control system 10 is illustrated by the followingnon-limiting example.

For a three week period of time, coagulant pump 26 is operated manuallyto provide a suitable amount of coagulant to produce an acceptableaqueous phase in line 22. During this period of time, the values of theparameters determined by components 34, 36, 38 and 40 are periodicallynoted along with the coagulant flowrate at the time these parameters aredetermined. Also, during this period of time, the flowrate of coagulantprovided to line 18 and/or the composition and/or flowrate of the wastewater in line 18 are varied over relatively wide ranges to aid indeveloping a coagulant flowrate/mixture parameters relationship havingrelatively broad applicability. The resulting data are then correlated,for example, using conventional and well know data correlationtechniques, to yield the relationship which is inputed through keyboard52 into electronic microprocessor 32.

The laundry waste water treatment system is then controlled by controlsystem 10. Thus, if the parameters measured by components 34, 36, 38 and40 indicate that more coagulant is needed, electronic microprocessor 32will send a control signal through line 24 instructing pump 26 to supplymore coagulant to line 18. Conversely, if the parameters measured bycomponents 34, 36, 38 and 40 indicate that less or the same amount ofcoagulant is needed, electronic microprocessor 32 will send a controlsignal through line 24 instructing pump 26 to supply less or the sameamount, respectively, of coagulant to line 18.

This on-line control mechanism is very effective in providing aclarified aqueous phase in line 22 which is acceptable for transport toa publically owned treatment works. In addition, the present controlsystem 10 is very effective in controlling the amount of coagulant usedso that the cost of providing this acceptable water phase is controlled,and preferably substantially minimized. Control system 10 is responsiveto changes in the composition of the waste water from laundry 12 so thatthe amount of coagulant can be increased or decreased depending upon theactual needs of the installation 1.

While this invention has been described with respect to various specificexamples and embodiments, it is to be understood that the invention isnot limited thereto and that it can be variously practiced within thescope of the following claims.

What is claimed is:
 1. A system constructed an arranged for controllingthe amount of cationic coagulant to be introduced into a laundry wastewater having a FOG level which is to be reduced, said systemcomprising:a first detector adapted to determine the turbidity of afirst material comprising a laundry waste water having a FOG level whichis to be reduced, and to provide a first signal indicative of saiddetermined turbidity; a second detector adapted to determine theelectric charge value of a second material comprising said laundry wastewater, and to provide a second signal indicative of said determinedelectric charge value, said first and second detectors each beingdownstream of the introduction of cationic coagulant and upstream of thereduction of FOG level; and an automatic processor provided with arelationship of the amount of cationic coagulant to be introduced intosaid laundry waste water to reduce the FOG of said laundry waste waterto a given level as a function of both said first signal and said secondsignal, and adapted to receive said first signal and said second signal,to process said first signal and said second signal in accordance withsaid relationship, and to provide a third signal to a source of cationiccoagulant to control the amount of a cationic coagulant introduced fromsaid source of cationic coagulant into said laundry waste water.
 2. Thesystem of claim 1 wherein said relationship is experimentally developed.3. The system of claim 1 wherein said first detector comprises aturbidimeter and said second detector comprises a streaming currentdetector.
 4. The system of claim 1 wherein said automatic processorcomprises a microprocessor.
 5. The system of claim 4 which furthercomprises a manual input device in communication with said automaticprocessor and adapted to be manually operated to provide saidrelationship to said automatic processor.
 6. The system of claim 1 whichfurther comprises at least one additional detector adapted to determinean additional parameter, other than the FOG level, of an additionalmaterial comprising said laundry waste water, and to provide anadditional signal indicative of said additional determined parameter,said relationship is further a function of said additional signal, andsaid automatic processor is further adapted to receive said additionalsignal and to process said additional signal, along with said firstsignal and said second signal, in accordance with said relationship. 7.The system of claim 1 which further comprises a pump adapted to pumpcationic coagulant into said laundry waste water, to receive said thirdsignal form said automatic processor, and to operate to pump cationiccoagulant into said laundry waste water in response to said thirdsignal.
 8. The system of claim 1 wherein said first and second materialsfurther comprise an at least partially effective amount of said cationiccoagulant.
 9. A system constructed and arranged for controlling theamount of a treatment composition to be introduced into an aqueousmedium having a FOG level which is to be reduced, said systemcomprising:a plurality of detectors each of which is adapted todetermine a different parameter, other than the FOG level, of a materialcomprising an aqueous medium having a FOG level which is to be reduced,and to provide a determined signal indicative of said determinedparameter, at least two of said plurality of detectors are downstream ofthe introduction of treatment composition and upstream of the reductionfo the FOG level; and an automatic processor provided with arelationship of the amount of treatment composition to be introducedinto said aqueous medium to reduce the FOG of said aqueous medium to agiven level as a function of said plurality of determined signals, andadapted to receive said plurality of determined signals and to provide acontrol signal to a source of treatment composition to control theamount of a treatment composition introduced from said source oftreatment composition into said aqueous medium.
 10. The system of claim9 wherein said relationship is experimentally developed.
 11. The systemof claim 9 wherein said automatic processor comprises a microprocessor.12. The system of claim 11 which further comprises a manual input devicein communication with said automatic processor and adapted to bemanually operated to provide said relationship to said automaticprocessor.
 13. The system of claim 9 which further comprises a pumpadapted to pump said treatment composition into said aqueous medium toreceive said control signal form said automatic processor, and tooperate to pump said treatment composition into said aqueous medium inresponse to said control signal.
 14. The system of claim 9 wherein atleast one said materials further comprises an at least partiallyeffective amount of said treatment composition.
 15. A method forcontrolling the amount of a treatment composition to be introduced intoan aqueous medium having a FOG level which is to be reduced, said methodcomprising:determining a plurality of different parameters, other thanFOG level, of one or more materials comprising an aqueous medium havinga FOG level which is to be reduced, at least two of said parametersbeing determined downstream of said introduction and upstream of saidreduction of the FOG level; generating a plurality of determined signalseach of which is indicative of one of said plurality of differentdetermined parameters; providing said plurality of determined signals toan automatic processor; providing said automatic processor with arelationship of the amount of a treatment composition to be introducedinto said aqueous medium to reduce the FOG level of said aqueous mediumto a given level as a function of said plurality of determined signals;generating a control signal from said automatic processor, said controlsignal being based on said automatic processor processing said pluralityof determined signals in accordance with said relationship; providingsaid control signal to a source of treatment composition which providessaid treatment composition to said aqueous medium; and operating saidsource of treatment composition in response to said control signal tocontrol the amount of said treatment composition from said source oftreatment composition to said aqueous medium.
 16. The method of claim 15which further comprises experimentally developing said relationship. 17.The method of claim 15 wherein said one or more materials furthercomprise an at least partially effective amount of said treatmentcomposition.
 18. The method of claim 15 wherein said aqueous medium is alaundry waste water, said parameters include turbidity and electriccharge value, and said treatment composition includes a cationiccoagulant.